Intermittent positive pressure breathing apparatus



May 16, 1967 F. N. WiNDSOR 3,319,627

INTERMITTENT POSITIVE PRESSURE BREATHING APPARATUS Filed Feb. 20, 1964 INVENTOR F2410 \X/nvosca,

United States Patent Ofifice 3,319,627 Patented May 16, 1967 3,319,627 INTERMITTENT POSITIVE PRESSURE BREATHING APPARATUS Fred N. Windsor, Pittsburgh, Pa., assignor to Mine Safety Appliances Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 20, 1964, Ser. No. 346,141 4 Claims. (Cl. 128145.6)

This invention relates to breathing apparatus in which a gas is delivered to the patient under pressure intermittently, and more particularly to means for adding to the gas a supplemental gas.

In the field of intermittent positive pressure breathing when air, for example, is used as the motivating force it sometimes is desirable to enrich or modify the air with another gas. This has been done in various ways. One device enriches the air by operating a nebulizer with oxygen, but the degree of enrichment is very limited due to the small orifices in the nebulizer. In another case enriching the air is done by aspirating oxygen from a demand valve through a venturi, but a drawback is that very little oxygen is aspirated when low flows are used for a patient. When high flows are employed, there will be a relatively large volume of oxygen aspirated during the first phase of inspiration, but as the back pressure builds up, both the air and the oxygen flow to the patient decreases.

It is among the objects of this invention to provide intermittent positive pressure breathing apparatus, in .which the volume of supplemental gas added to the motivating gas is entirely independent of a nebulizer or venturi, in which the flow rate of the added gas can be varied from a very few liters a minute to rates in excess of 100 liters per minute, and in which the flow rate can be held constant throughout the full inspiration.

In accordance with this invention a conduit has a nozzle at its outlet end provided with a restricted passage. Means are provided for intermittently supplying compressed gas through the conduit to the nozzle. When the source of compressed gas is a continuously operating air compressor, an intermittently operating valve is placed in the conduit. A tube receives the gas from the nozzle and has an outlet adapted to deliver the gas to a patient. A normally closed valve has an inlet for connection to a source of supplemental gas, such as a tank of compressed oxygen and it also has an outlet connected with the tube. This valve is opened when pressure-responsive means is operated by the gas pressure in the conduit. Thereupon, supplemental gas is delivered to the gas flowing through the tube from the nozzle.

The preferred embodiment of the invention is illustrated in the accompanying drawing, in which the single figure is a combination side view and section of my apparatus.

Referring to the drawing a tube, such as a venturi tube 1 when the motivating gas is air, has an outlet that may be connected by a flexible hose 2 to a mouthpiece or mask worn by a patient to whom a gas mixture is to be delivered under pressure. Mounted in the inlet end of the tube is a nozzle 3 having a small passage 4 through it to form a flow restriction. The nozzle is connected to one end of a conduit 6, the opposite end of which is connected to a source of compressed gas, such as a tank, or a continuously operating centrifugal compressor 7 when the gas is air. The conduit also is provided with a valve 8, preferably electrically operated, that is opened and closed continually so that a gas will be delivered under pressure to the patient every time he inhales. Intermittent opening of the valve can be effected in any well-known manner, such as'by a normally open pressure operated electric switch 9 that is closed every time the patient creates a slight negative pressure by starting to inhale. Then, when the gas pressure in the patients lungs reaches a predetermined level the valve closes so that he can exhale through a conventional exhalation valve or, where air is being administered, through the ventruri tube and an opening 10 at its inlet end open to the atmosphere.

It is a feature of this invention that another gas, such as oxygen for example, is added to the compressed gas before it reaches the patient, and that the added gas is supplied at a constant rate. Accordingly, one side of the outlet end of the venturi tube is provided with an inlet 12 that may be connected by a tube 13 to the outlet of a normally closed oxygen valve 14. The inlet of the valve housing is connected by a tube 15 through a throttling or pressure reducing valve 16 to a source of oxygen under pressure, such as an oxygen tank 17. The valve includes a port 18 encircled by a seat 19, against which a closure member 20 may be pressed by a spring 21. The closure member is provided with an upwardly extending stem 22, the upper end of which is connected to pressure-responsive means for pushing the closure memher down away from its seat. Preferably, such means consists of a flexible diaphragm 23. To flex the diaphragm downward periodically, the valve chamber 24 above it is connected by a tube 25 to the air conduit between valve 8 and the nozzle.

In operation, every time valve 8 is opened, the air from the compressor flows through the nozzle and the venturi nozzle builds up in conduit 6 and, because of its connection through tube 25 with valve chamber 24, the air pressure depresses the diaphragm and thereby opens the oxygen valve. Oxygen then flows from the tank through valve 14 and tube 13 into the outlet end of the venturi tube to mix with the air before reaching the patient. The moment that valve 8 closes to permit exhalation, the air pressure above the diaphragm escapes through tube 25 and the nozzle into the venturi tube and then out through its opening 16 to the atmosphere. This allows the spring or the oxygen pressure to close the oxygen valve so that no oxygen is lost during exhalation. If tube 1 did not have an opening 10, the gas pressure above the diaphragm would escape through tube 25 and the nozzle and into the tube, which would be at a lower pressure because the patients exhalation valve would be open.

It will be seen that the volume and rate of flow of the supplemental gas into the system is independent of the main flow through the venturi. It depends only on the setting of valve 16. Therefore, for any given setting the flow rate remains constant, thereby ensuring adequate oxygen enrichment at low flow or at the end of inspiration.

According to the provisions of the patent statutes, 1 have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than is specifically illustrated and described.

I claim:

1. Intermittent positive pressure breathing apparatus comprising a conduit having an outlet end, a nozzle connected to said end of the conduit and provided with a restricted passage, means for intermittently supplying compressed gas through said conduit to the nozzle, a tube for receiving gas from said nozzle at a lower pressure than it enters the nozzle and having an outlet adapted to deliver said gas to a patient, a valve housing having an inlet for connection to a supplemental gas source and having an outlet connected with said tube, said housing containing a valve port, a closure member at the inlet side of said port normally closing the port, a stem extending through the port and connected at one end of the closure member, a flexible diaphragm mounted in the housing and engaging the opposite end of said stern, said valve outlet being located between said port and one side of the diaphragm, and means connecting said conduit with the inside of saidhousing at the opposite side of the diaphragm so that gas pressure in the conduit will flex the diaphragm and cause it to push said closure member away from said port.

2. Intermittent positive pressure breathing apparatus comprising a conduit having an outlet end, a nozzle connected to said end of the conduit and provided with a restricted passage, means for intermittently supplying compressed air through said conduit to the nozzle, 21 venturi tube for receiving air from said nozzle and having an outlet adapted to deliver said air to a patient, the nozzle end of the venturi being provided with an opening open to the atmosphere, a normally closed valve having an inlet for connection to a supplemental gas source and having an outlet connected With the side of the outlet end of the venturi tube, pressure-responsive means operable to open said valve, and means connecting said conduit with said pressure-responsive means so that air pressure in the conduit will operate the pressure-responsive means to deliver said gas to the air flowing through the venturi tube.

3. Intermittent positive pressure breathing apparatus comprising tubular conducting means having an inlet, means for intermittently supplying compressed gas to said inlet, said tubular means having an outlet adapted to deliver said gas to a patient, the tubular means containing means forming a restricted passage therein in a predetermined location, a Valve housing having an inlet for connection to a supplemental gas source and having an outlet adapted to deliver the supplemetal gas to the patient,

' said housing containing a valve port, a closure member at the inlet side of said port normally closing the port, a stem extending through the port and connected at one end to the closure member, a flexible diaphragm mounted in the housing and engaging the opposite end of said stem, said valve outlet being located between said port and one side of the diaphragm, and means connecting said tubular conducting means at the upstream end of said restricted passage with the inside of said housing at the opposite side of the diaphragm so that gas pressure in the tubular means While compressed gas is being supplied thereto can flex the diaphragm to open said valve.

3. Intermittent positive pressure breathing apparatus comprising tubular conducting means having an inlet, means for intermittently supplying compressed gas to said inlet, said tubular means having a outlet adapted to deliver said gas to a patient, the tubular means containing means forming a restricted passage therein in a predetermined location, a valve housing having an inlet for connection to a supplemental gas source and having anoutlet adapted to deliver the supplemental gas to the patient, said housing containing a valve port, a closure 7 member normally closing the port, fluid pressure responsive means mounted in the housing and operatively connected With said closure member, said valve housing outlet bein located between said port and one side of said pressure responsive means, and means connecting said tubular conducting means at the upstream end of said restricted passage with the inside of said housing at the opposite side of said pressure responsive means so that gas pressure in the tubular means while compressed gas is being supplied thereto can actuate the pressure responsive means and cause it to move said closure member away from said port.

References Cited by the Examiner UNITED STATES PATENTS 2,617,411 11/1952 Seeler.

2,948,292 8/1960 Fitt 128l42 3,138,152 6/1964 Wilson.

3,164,149 1/1965 White et al.

3,200,816 8/1965 Bartlet 128-142 RICHARD A. GAUDET, Primary Examiner.

C. F. ROSENBAUM, Assistant Examiner. 

1. INTERMITTENT POSITIVE PRESSURE BREATHING APPARATUS COMPRISING A CONDUIT HAVING AN OUTLET END, A NOZZLE CONNECTED TO SAID END OF THE CONDUIT AND PROVIDED WITH A RESTRICTED PASSAGE, MEANS FOR INTERMITTENTLY SUPPLYING COMPRESSED GAS THROUGH SAID CONDUIT TO THE NOZZLE, A TUBE FOR RECEIVING GAS FROM SAID NOZZLE AT A LOWER PRESSURE THAN IT ENTERS THE NOZZLE AND HAVING AN OUTLET ADAPTED TO DELIVER SAID GAS TO A PATIENT, A VALVE HOUSING HAVING AN INLET FOR CONNECTION TO A SUPPLEMENTAL GAS SOURCE AND HAVING AN OUTLET CONNECTED WITH SAID TUBE, SAID HOUSING CONTAINING A VALVE PORT, A CLOSURE MEMBER AT THE INLET SIDE OF SAID PORT NORMALLY CLOSING THE PORT, A STEM EXTENDING THROUGH THE PORT AND CONNECTED AT ONE END OF THE CLOSURE MEMBER, A FLEXIBLE DIAPHRAGM MOUNTED IN THE HOUSING AND ENGAGING THE OPPOSITE END OF SAID STEM, SAID VALVE OUTLET BEING LOCATED BETWEEN SAID PORT AND ONE SIDE OF THE DIAPHRAGM, AND MEANS CONNECTING SAID CONDUIT WITH THE INSIDE OF SAID HOUSING AT THE OPPOSITE SIDE OF THE DIAPHRAGM SO THAT GAS PRESSURE IN THE CONDUIT WILL FLEX THE DIAPHRAGM AND CAUSE IT TO PUSH SAID CLOSURE MEMBER AWAY FROM SAID PORT. 